Electric discharge device



F. R. ELDER ELECTRIC DI SCH ARGE DEVICE Filed May 21, 1946 Fig.1.

3 i i 1 i Inventor: prank 1?. Elder,

ahka His Attorney.

Patented Oct. 25, 1949 ELECTRIC DISCHARGE DEVICE Frank R. Elder, Niskayuna, N. Y., assignor to General Electric Company, a corporation of New York Application May 21, 1946, Serial No. 671,198

Claims. (Cl. 250-275) My invention relates to improved electric discharge devices and particularly to discharge devices for high voltage application.

High voltage electric discharge devices employing a pair of principal electrodes at opposite ends of an elongated envelope have been provided with a plurality of apertured metal plates mounted in spaced and insulated relation between the principal electrodes. These apertured electrodes have served to distribute voltage from one end of the envelope to the other and to increase the voltage at which the device may be operated. In the prior art constructions, however, the voltage rating of the tube has not been maintained over a long period of operation and its useful life has accordingly been materially shortened. In accordance with an important aspect of my invention I provide an electric discharge device including improved voltage dividing electrodes which also serve to shield the envelope from metal or other material which is liberated during operation of the tube and which tends to deposit on the walls of the envelope.

It is an object of my invention to provide a new and improved high voltage electric discharge device.

It is another object of my invention to provide a new and improved electric discharge device with particular reference to the ability of the device to withstand high operating voltages over a long period.

Further objects and advantages of my invention will become apparent as the following description proceeds, reference being had to the accompanying drawing in which Fig. 1 is an elevational view, in section, of an electric discharge device embodying my invention, and Fig. 2 is a similar View of a modified form of my invention.

Referring now to Fig. 1, I have shown my invention embodied in an electric discharge device of the type employing an ionizable medium, such as mercury vapor, and comprising an elongated generally cylindrical envelope I having a reentrant stem portion 2 formed at one end thereof. The cathode of the discharge device, which may be of any one of a number of known constructions, is supported from the upper end of the stem and, as illustrated, is enclosed in a generally cylindrical shield member 3. The cathode (not visible in the drawing) is provided with a center terminal and two end terminals connected respectively with conductors 4, 5 and 6 which, are sealed through the stem 2. Conductors 5 and 6 are connected together and to a terminal prong I while conductor 4 is connected to terminal prong 8. The prongs 1 and 8 form a part of a conventional tube base including a metallic band 9 surrounding the end of the envelope l and 2 joined thereto by a body of cement Ill. The shield 3 is supported from conductors 5 and 6 in insulated relation with respect thereto by insulating beads H.

The anode of the device is supported from the opposite end of the envelope and, as illustrated, is supported from a re-entrant flange I2 formed integrally with the end wall of the envelope. The anode includes a disk-like support or base member l3 which is sealed to the flange I2 by a metal flange I4 which is sealed at one end to the flange l 2 and welded at the other end to the base member IS. The anode proper is provided by a sheet metal member l5 which is of generally circular cross section and which is joined at its open end to the edge of the supporting disk l3. The opposite end of the anode is deformed in a longitudinal plane to provide a central planar portion l6 which is the discharge receiving portion of the anode,

and a surrounding offset portion which in the particular embodiment illustrated is in the form of a circular rib I! of V-shaped cross section. As will be apparent from an inspection of the drawing, the face of the anode corresponds in shape to the voltage dividing electrodes 18 to 23, inclusive, which will be described in more detail at a later point in the specification. The supporting member I 3 for the anode is provided with a plurality of openings 24 which render it possible to evacuate the interior of the anode during manufacture of the device. An externally accessible terminal for the anode is provided by a stud 25 threaded into a suitable upstanding flange 26 joined to the'central portion of the upper surface of the anode support l3.

The voltage dividing electrodes H to 23, inclusive, extend transversely of the envelope in spaced and mutually insulated relation throughout the longitudinal distance from the anode to the oathode. The voltage dividing electrodes are stamped or drawn to desired shape and annealed so that they are easily deformed. The edge portions are slotted, as shown at 2?, to facilitate the bending of the marginal portions of the electrodes into the mounting grooves 28 formed on the wall of the envelope. In assembly of the device, the envelope is formed in two sections, one of which is provided with a plurality of grooves, and the electrodes I8 to 23 are individually inserted and expanded into the appropriate grooves. It will be readily appreciated that the marginal portions of the voltage dividing electrodes may extend through the envelope wall and be separated by insulating cylinders which are sealed at opposite ends adjacent electrodes. The central portion of each of the voltage dividing electrodes is provided with an aperture 29 through which the discharge between the anode and cathode. takes place, and each opening is surrounded by a ridge or rib 30 of V-shaped cross section as described in connection with the face of the anode I5. The p c g of the voltage dividing electrodes and the height of the rib of each electrode are preferably chosen so that the wall of the envelope is completely shielded; that is to say, the height of the rib is equal to or greater than the distance between adjacent electrodes. If desired, the region of ionization about the cathode may be minimized by providing a cylindrical metal shield, as illustrated at 33', which depends from the lower electrode 23 and surrounds the cathode cylinder 3.

It will be readily understood by those skilled in the art that single Wires or a wire mesh may be provided over the apertures in the voltage dividing electrodes 18 to 23. These wires or grids serve to distribute the current of the discharge device and to decrease the deionization time by decreasing the distance that an ion is required to travel before it impinges on a collecting surface. However, the presence of such wires or wire mesh may increase the pick-up voltage of the device which may be oifset by increasing the operating pressure of the ionizable medium employed.

I have found that with the voltage dividing electrode construction described above, with or without wires or mesh substantially no metal or other material is deposited on the glass walls of the envelope during prolonged periods of operation, and that the voltage dividing function of the electrodes is retained throughout the life of the tube.

In Fig. 2 I have shown a modification of my invention which in general is similar to that shown in Fig. 1 but in which the voltage dividing electrodes are of different shape. In Fig. 2, parts corresponding to parts of Fig. l have been designated by the same reference numerals. In Fig. 2 it will be noted that the anode member I5 is simply a hollow cylindrical body having a planar face It. It will also be noted that the voltage dividing electrodes H to 23' are substantially planar throughout the central region of the interior of the envelope. The shielding of the envelope wall is accomplished by cylindrical flanges 34 and 35 secured to the bottom and top, respectively, of the voltage dividing electrodes. It will be noted that no flange 35 is provided on the uppermost electrode ll since the anode in this particular illustration is provided with a planar surface. While the modification of Fig. 2 is relatively simple to make and satisfactory for some purposes, it will be readily appreciated that with the same degree of shielding the minimum clearance between adjacent voltage dividing electrode assemblies is somewhat less than it is when the construction of Fig. 1 is employed.

In the following claims the work nested has been employed to define the relationship of adjacent voltage dividing electrodes. As employed the word is intended to define the relationship existing in both Figs. 1 and 2 and not to be limited to an interfitting relationship of objects of graduated size.

While I have shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention in its broader aspects, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A high voltage electric discharge device comprising an elongated envelope, an anode and a cathode supported within said envelope in longitudinally spaced relation, a plurality of voltage dividing electrodes supported in longitudinally spaced and mutually insulated relation between said anode and cathode and extending generally transversely of the envelope, said electrodes having aligned openings defining a discharge path between said anode and cathode and each provided with a generally circular ridge of generally V-shaped cross section surrounding the opening, the ridges of adjacent electrodes being arranged in nested relation so that the wall portions of the envelope between the voltage dividing electrodes are completely shielded by said ridges.

2. A high voltage electric discharge device comprising an elongated envelope, an anode and a cathode supported within said envelope in longitudinally spaced relation, and a'plurality of voltage dividing electrodes supported in longitudinally spaced and mutually insulated relation between said anode and cathode and extending generally transversely of the envelope, said electrodes each having an opening defining a'discharge path between said anode and cathode and each provided with a ridge surrounding the opening, said ridge forming a corresponding recess on the opposite side of the electrode, the ridge of each electrode extending into the recess of the adjacent electrode so that the wall portions of the envelope between the voltage dividing electrodes are completely shielded by said ridges.

3. A high voltage electric discharge device comprising an elongated envelope of insulating material, an anode and .a cathode supported within said envelope. in longitudinally spaced relation, and a plurality of voltage dividing electrodes supported in longitudinally spaced and mutually insulated relation between said anode and cathode and extending generally transversely of the envelope, said electrodes each having an opening defining a discharge path between said anode and cathode and each provided with a ridge surrounding the opening, said ridge forming a corresponding recess on the opposite side of the electrode, the ridge of each electrode extending into the recess of the adjacent electrode so that the wall portions of the envelope between the voltage dividing electrodes are shielded by said ridges, said anode having a ridge formed on the face thereof and extending into the recess of the electrode adjacent the anode.

4. An electric discharge device comprising an elongated envelope, an anode and a cathode supported Within said envelope in longitudinally spaced relation, an electrode supported between said anode and cathode in insulated relation with respect thereto and extending generally transversely of the envelope, said electrode having an opening defining a discharge path between said anode and cathode, the face of said anode and said electrode having portions ex.- tending in longitudinally overlappin relation to shield said envelope in the region between said anode and cathode.

5. An electric discharge device comprising an envelope of insulating material, an anode and a 5 6 cathode supported within said envelope in longitudinally spaced relation, an electrode extend- REFERENCES CITED ing transversely of said envelope and having an The following references are of record in the opening defining a discharge path between said file of this patent: anode and cathode, said envelope having an out- 5 wardly extending recess in the side wall thereof, UNITED STATES PATENTS said electrode having a resilient marginal por- Number Name Date tion received in and engaging the walls of said 1,963,051 Kuntke June 12, 1934 recess. 1,963,059 Mulder et a1. June 12, 1934 FRANK R. ELDER. 10 2,020,077 Mulder et a1 Nov. 5, 1935 

